The present invention relates to elastic films, and more particularly, to elastic films having high tear-strength and low set. Elastic films of the present invention having high tear-strength and low set exhibit surprisingly high tear resistance, especially when holes form on the films.
Elastic films of the present invention have a wide range of potential uses in both durable and disposable articles, but are particularly well suited for use in elastic waistbands and in products including absorbent products and the like.
The present invention relates to the coextrusion of a thin multi-layer elastic film that stretches in the transverse direction. The elastic film has a first layer, a second layer and a core layer. The film has activation zones and non-activated zones. The activated zones have sufficient elasticity to stretch to at least 200% while maintaining a permanent set percent of no more than 5%. The non-activated zones have sufficient non-elastic to stretch at least 200% while maintaining a permanent set percent of up to 5%. The activated zones have a tear strength as measured by the Elmendorf Tear Test of 30 g while the non-activated zones have a tear strength as measured by the Elmendorf Tear Test of at least 50 g. The elastic film is particularly useful as an elastic waistband for use in products including absorbent products such as waist bands, side panels and the like. The superior tear-strength of the film prevents tearing during use of the film and promotes longer-lasting applications of the film., In addition, the superior tear-strength of the film prevents existing tears from propagating throughout the film. For ease of illustration, a thin multi-layer coextruded elastomeric film is described in detail herein in FIGS. 1-7. However, this detailed description will allow those skilled in the art to adapt this invention to produce elastomeric film for other applications.